Method for manufacturing reclosable packaging bag

ABSTRACT

A reclosable packaging bag comprises a main bag body having an opening portion and at least one heat-sealed portion; and a linear fastener provided on the opening portion of the main bag body. The linear fastener is provided along the opening portion of the main bag body by an insert injection molding so as not to extend to the heat-sealed portions. A method for manufacturing the bag comprises the three steps. First, the first and second linear fastening members are formed on a prescribed position of a sheet of film material by an insert injection molding so as to be spaced from each other. These fastening members are engageable with each other to form a linear fastener. Second, the sheet of film material is folded in two so that the fastening members can engage with each other. Third, each of opposite portions of the sheet of film material thus folded is heat-sealed to form side heat-sealed portions.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. application Ser. No.09/799,809, filed Mar. 7, 2001, now U.S. Pat. No. 6,908,422,incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a packaging bag that can be reopenedand reclosed, and a method for manufacturing such a reclosable packagingbag.

2. Description of the Related Art

A reclosable packaging bag 1, which has conventionally been used,comprises a main bag body 7 and a linear fastener 9 as shown in FIG. 25.The main bag body 7 is formed by placing two sheets of plastic filmmaterial 2, 3 one upon another and heat-sealing the opposite side edgesand the lower edge of them so that the main bag body 7 has an upperopening portion 8 and heat-sealed portions 4, 5, 6. The linear fastener9 is provided on the inner surface of the opening portion 8 of the mainbag body 7. The opening edge of the reclosable packaging bag 1 is closedby subjecting the opening edge to a heat sealing process after fillingthe bag 1 with the contents. The linear fastener 9 is composed of afastening member having a male-engaging portion and the other fasteningmember having a female-engaging portion.

With respect to the manufacturing method of the above-mentionedreclosable packaging bag, the linear fastener 9 is cut off to a length,which is identical to the width of the sheets of plastic film material2, 3, in order to provide the main bag body 7 with the linear fastener9. The one fastening member of the linear fastener 9 thus cut istemporarily bonded on the inner surface of the one edge of the sheet 2.The other fastening member of the linear fastener 9 thus cut istemporarily bonded on the inner surface of the one edge of the sheet 3.The heat-sealing process, which is applied to the sheets 2, 3 to formthe main bag body 7, causes the fastening members of the linear fastener9 to be secured firmly on the inner surface of the main bag body 7.

In the above-mentioned conventional reclosable packaging bag, the linearfastener 9 extends continuously from the outer edge of the heat-sealedportion locating on the one side of the main bag body to the outer edgeof the heat-sealed portion locating on the other side of the main bagbody. Consequently, each of both side portions of the main bag body hasa thickness, which is identical to the total of the thickness of the twosheets and the thickness of the fastening members. There is requiredenough pressure and quantity of heat by which the fastening members canbe melted and deformed, when applying the heat-sealing process to theopposite sides of the main bag body. A required period of time for theheat-sealing process is therefore extended.

The step for cutting off the linear fastener to the length, which isidentical to the width of the sheets of plastic film material, and thestep for bonding the fastening members for the linear fastener on theinner surfaces of the sheets of plastic film material are essential tothe method for manufacturing the above-mentioned reclosable packagingbag. Improvement in processing efficiency may be restricted.

In general, the reclosable packaging bag has so small rigidity that thereclosable packaging bags receiving the contents cannot be exhibited asmerchandise in a stacked state.

SUMMARY OF THE INVENTION

An object of the present invention, which was made in view of theabove-described problems, is to provide a reclosable packaging bag and amethod for manufacturing such a bag, which permit to reduce the periodof time for process and improve the processing efficiency.

Another object of the present invention is to provide a reclosablepackaging bag, which is stackable.

In order to solve the object concerning the period of time for processand the processing efficiency, a reclosable packaging bag of the presentinvention comprises:

a main bag body having an opening portion and at least one heat-sealedportion; and

a linear fastener provided on said opening portion of said main bagbody,

wherein:

said linear fastener is provided along said opening portion of said mainbag body by an insert injection molding so as not to extend to saidheat-sealed portions.

The heat sealed portion may be provided on each of opposite sides ofsaid main bag body.

The heat sealed portion may be provided on one of a pair of opposingfaces of said main bag body;

The heat-sealed portion may be provided on a middle portion of said oneof said pair of opposing faces.

The reclosable packaging bag may comprise a sleeve, which is placed insaid main bag body to keep a prescribed shape thereof.

The sleeve may be foldable.

The sleeve may have a pair of projections each having a triangularshape, said pair of projections being capable of coming into contactwith a bottom of said main bag body and being foldable.

The sleeve may have at least one bendable reinforcement flap, whichlocates in a vicinity of said opening portion of said main bag body.

The sleeve may have a detachable sleeve portion that is accessible whenthe reclosable packaging bag is opened and which when detached enablesthe sleeve to relax from said prescribed three-dimensional shape.

Finger-holes may be formed in said detachable sleeve portion tofacilitate its removal.

The main bag body may be folded into a prescribed shape; and the linearfastener may have easily bendable portions, which facilitates thefolding of said main bag body.

The linear fastener may have a female-fastening member and amale-fastening member engageable therewith, and said easily bendableportions may comprise flat portions, which are formed by removingpartially said female-fastening member and said male-fastening member.

The flat portions may have auxiliary sealing means, said auxiliarysealing means being capable of coming into contact with each other toseal a space between said flat portions.

The main bag body may have at least one stopper portion for positioningsaid sleeve.

In order to solve the object concerning the stackable property, areclosable packaging bag of the present invention comprises:

a main bag body having an opening portion and at least one heat-sealedportion; and

a linear fastener provided on said opening portion of said main bagbody,

wherein:

said reclosable packaging bag further comprises a sleeve, which isplaced in said main bag body, said main bag body being folded into aprescribed three-dimensional shape defined by said sleeve so as to keepsaid prescribed three-dimensional shape.

In order to solve the object concerning the period of time for processand the processing efficiency, a method of the present invention formanufacturing the reclosable packaging bag comprises the steps of:

forming first and second linear fastening members on a prescribedposition of a sheet of film material by an insert injection molding soas to be spaced from each other, said first and second linear fasteningmembers being engageable with each other to form a linear fastener;

folding said sheet of film material having said first and second linearfastening members formed thereon in two so that said first and secondlinear fastening members can engage with each other; and

heat-sealing each of opposite portions of said sheet of film materialthus folded to form side heat-sealed portions.

In order to solve the object concerning the period of time for processand the processing efficiency, another method of the present inventionfor manufacturing the reclosable packaging bag comprises the steps of:

continuously forming first and second linear fastening members on aprescribed position of a rolled strip of film material by an insertinjection molding so as to be spaced from each other, said first andsecond linear fastening members being engageable with each other to forma linear fastener;

cutting said rolled strip of film material into a separately independentsheet of film material;

folding said sheet of film material having said first and second linearfastening members formed thereon in two so that said first and secondlinear fastening members can engage with each other; and

heat-sealing each of opposite portions of said sheet of film materialthus folded to form side heat-sealed portions.

The linear fastener may continuously be formed on said sheet of filmmaterial so as not to extend to said heat-sealed portions.

In order to solve the object concerning the period of time for processand the processing efficiency, a further another method of the presentinvention for manufacturing the reclosable packaging bag comprises thesteps of:

folding a single sheet of film material in two to prepare a non-joinedmain bag body, upper and opposite side edges of which have not as yetbeen joined with each other;

folding upper portions of said non-joined main bag body so as to beseparate from each other to form a pair of bent portions;

placing said pair of bent portions in a linear-fastener molding machine;

continuously forming fist and second linear fastening members for alinear fastener on inner surfaces of said pair of bent portions of saidmain body by an insert injection molding, respectively, excludingopposite side edges thereof; and

heat-sealing said opposite side edges of said non-joined main bag bodyover their entirety.

In order to solve the object concerning the period of time for processand the processing efficiency, a still further another method of thepresent invention for manufacturing the reclosable packaging bagcomprises the steps of:

folding a single sheet of film material in two to prepare a non-joinedmain bag body, upper and lower edges and one of opposite side edges ofwhich have not as yet been joined with each other;

forming a cut-out on an upper end of the other of said opposite sideedges of said non-joined main bag body;

folding upper portions of said non-joined main bag body so as to beseparate from each other to form a pair of bent portions, said upperportions having a length corresponding to a length of said cut-out;

placing said pair of bent portions in a linear-fastener molding machine;

continuously forming fist and second linear fastening members for alinear fastener on inner surfaces of said pair of bent portions of saidnon-joined main bag body by an insert injection molding, respectively,excluding opposite side edges thereof; and

heat-sealing said lower edge and said one of opposite side edges of saidnon-joined main bag body over their entirety and heat-sealing only saidupper end of said other of said opposite side edges of said non-joinedmain bag body.

In order to solve the object concerning the period of time for processand the processing efficiency, a still further another method of thepresent invention for manufacturing the reclosable packaging bagcomprises the steps of:

placing opposite edges of a single sheet of film material one uponanother and heat-sealing overlapping portions of said single sheet offilm material over their entirety in a longitudinal direction to form aheat-sealed portion, so as to prepare a non-joined main bag body, upperand lower ends are opened;

folding said non-joined main bag body in a flat state so that said heatsealed portion locates apart from one of opposite side edges of saidnon-joined main bag body by a prescribed distance;

forming cut-outs on upper ends of said opposite side edges of saidnon-joined main bag body;

folding upper portions of said non-joined main bag body so as to beseparate from each other to form a pair of bent portions, said upperportions having a length corresponding to a length of said cut-out;

placing said pair of bent portions in a linear-fastener molding machine;

continuously forming fist and second linear fastening members for alinear fastener on inner surfaces of said pair of bent portions of saidnon-joined main bag body by an insert injection molding, respectively,excluding opposite side edges thereof; and

heat-sealing a lower edge of said non-joined main bag body over itsentirety and heat-sealing only said upper ends of said opposite sideedges of said non-joined main bag body.

In order to solve the object concerning the period of time for processand the processing efficiency, a still further another method of thepresent invention for manufacturing the reclosable packaging bagcomprises the steps of:

placing at least two sheets of film material one upon another to preparea non-joined main bag body, upper and lower opposite edges and left-handand right-hand side edges of which have not as yet been joined with eachother;

folding upper portions of said at least two sheets of film material soas to be separate from each other to form a pair of bent portions;

placing said pair of bent portions in a linear-fastener molding machine;

continuously forming fist and second linear fastening members for alinear fastener on inner surfaces of said pair of bent portions of saidnon-joined main bag body by an insert injection molding, respectively,excluding opposite side edges thereof; and

heat-sealing said lower edge and said left-hand and right-hand sideedges of said non-joined main bag body over their entirety.

The method may further comprise the step of inserting a sleeve forkeeping a prescribed shape of said main bag body thereinto, aftercompletion of the final step.

The method may further comprise the step of placing a sleeve for keepinga prescribed shape of said main bag body in said non-joined main gabbody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an embodiment of the reclosable packaging bagof the present invention;

FIG. 2 is a view illustrating the linear fastener of the reclosablepackaging bag as shown in FIG. 1;

FIG. 3 is a view illustrating an example of the method for forming thelinear fastener as shown in FIG. 2;

FIG. 4 is a view illustrating another example of the method for formingthe linear fastener as shown in FIG. 2;

FIG. 5 is a view illustrating the linear fastener, which is formed inaccordance with the linear fastener forming method as illustrated inFIG. 4;

FIG. 6 is a plan view of another embodiment of the reclosable packagingbag of the present invention;

FIG. 7 is a view illustrating the first stage of the packaging processof the reclosable packaging bag of the present invention, in which thecontents having a rectangular plate-shape are received;

FIG. 8 is a view illustrating the second stage of the packaging processof the reclosable packaging bag of the present invention, in which thecontents having a rectangular plate-shape are received;

FIG. 9 is a view illustrating the third stage of the packaging processof the reclosable packaging bag of the present invention, in which thecontents having a rectangular plate-shape are received;

FIG. 10 is a view illustrating a packaged article, which is obtained byfilling the reclosable packaging bag with the contents having therectangular plate-shape;

FIG. 11 is a plan view of another embodiment of the reclosable packagingbag of the present invention;

FIG. 12 is a schematic view of a sleeve used in the reclosable packagingbag as shown in FIG. 11;

FIG. 13 is a partial perspective view illustrating an easily bendableportion of the linear fastener of the reclosable packaging bag as shownin FIG. 11;

FIG. 14 is a cross-sectional view illustrating an auxiliary sealingmeans provided on the easily bendable portion as shown in FIG. 13;

FIG. 15 is a cross-sectional view illustrating a modification of theauxiliary sealing means as shown in FIG. 14;

FIG. 16 is a schematic view illustrating steps for manufacturing thereclosable packaging bag of the present invention;

FIG. 17 is a schematic view illustrating the other steps formanufacturing the reclosable packaging bag of the present invention;

FIG. 18 is a plan view of further another embodiment of the reclosablepackaging bag of the present invention;

FIG. 19 is a partial enlarged view illustrating the stopper portion ofthe reclosable packaging bag as shown in FIG. 18;

FIG. 20 is a view illustrating a modification of the sleeve as shown inFIG. 18;

FIG. 21 is a view illustrating a modification of the sleeve as shown inFIG. 20;

FIG. 22 is a perspective view illustrating an example of abottom-formation method used in the reclosable packaging bag of thepresent invention;

FIG. 23 is a perspective view illustrating another example of abottom-formation method used in the reclosable packaging bag of thepresent invention;

FIG. 24 is a view illustrating the bottom of the reclosable packagingbag, which is obtained by the example of the bottom-formation method asshown in FIG. 23; and

FIG. 25 is a plan view of the conventional reclosable packaging bag.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

FIG. 1 illustrates an example in which a reclosable packaging bag of thepresent invention is applied to a self-standing type reclosablepackaging bag. The self-standing type reclosable packaging bag 10comprises a main bag body 14 and a linear fastener 15. The main bag body14 is composed of two sheets of film material 11, 12 for forming theopposite faces of the bag and of a sheet of film material 13 for formingthe bottom of the bag. The linear fastener 15 is provided on the innersurface of the opening portion of the main bag body 14.

The above-mentioned main bag body 14 is prepared by folding the sheet offilm material 13 in two, placing the thus folded sheet of film material13 between the respective lower portions of the sheets of film material11, 12 so that the folding edge 13 a of the folded sheet of filmmaterial 13 is directed upward, heat-sealing the opposite side portionsof the sheets of film material 11, 12 to form side heat-sealed portions16, 16 and heat-sealing the lower portions of the sheets of filmmaterial 11, 12 to form a heat-sealed lower portion 17.

The above-mentioned sheets of film material 11, 12, 13 are formed of thesame plastic film material. As such a sheet of film material, there canbe used for example a laminate film composed of a polyester film havinga thickness of 12 μm, an aluminum foil having a thickness of 9 μm and apolyethylene film having a thickness of 50 μm, or a laminate filmcomposed of a polyester film having a thickness of 12 μm and apolyethylene film having a thickness of 50 μm.

The above-mentioned linear fastener 15 is composed of a female-fasteningmember 18 and a male-fastening member 19 as shown in FIG. 2. The linearfastener 15 is provided along the opening end of the main bag body 14and has a length corresponding to a value, which is obtained bysubtracting the total width of the side heat-sealed portions 16, 16 fromthe entire width of the main bag body 14, as shown in FIG. 1.

Contents received in the self-standing type reclosable packaging bag 10may have a square or rectangular plate-shape. In such a case, theself-standing type reclosable packaging bag 10 can be deformed into acube or a rectangular parallelepiped. It is preferable to provide easilybendable portions such as notches on portions to be bent of thefemale-fastening member 18 and the male-fastening member 19 of thelinear fastener 15 in order to facilitate such deformation of the bag.It is also preferable to reduce the thickness of the both end portionsof the female-fastening member 18 and the male-fastening member 19 toform thin portions.

FIG. 2 illustrates an example in which the female-fastening member 18and the male-fastening member 19 that form the linear fastener 15 arejoined to the main bag body 14 during the forming process of the mainbag body 14. The female-fastening member 18 and the male-fasteningmember 19 are joined to the upper portions 11 a, 12 a of the sheets offilm material 11, 12 for the main bag body 14, respectively. Theopposite side edges of the upper portions 11 a, 12 a are not joined witheach other.

More specifically, the upper portions 11 a, 12 a of the sheets of filmmaterial 11, 12, having the opposite side edges, which have not as yetbeen joined with each other, are bent at right angles in oppositedirections so as to be separate from each other. The upper portions 11a, 12 a thus bent are placed between dies 20 and 21 of a linear-fastenermolding machine as shown in FIG. 3. Then, synthetic resin such aspolyethylene resin is injected in a molten state from a gate 22 of thedie 21 to molding spaces through runners 23, 23 by an insert injectionmolding. Consequently, the female-fastening member 18 and themale-fastening member 19 are joined onto the inner surfaces of the bentupper portions 11 a, 12 a. Each of the female-fastening member 18 andthe male-fastening member 19 has a smaller length than the entire widthof the main bag body 14. More specifically, both of them have a lengthcorresponding to a value, which is obtained by subtracting the totalwidth of the side heat-sealed portions 16, 16 that are to be formed by asubsequent process, from the entire width of the main bag body 14.

FIG. 4 illustrates an example in which the female-fastening member 18and the male-fastening member 19 that form the linear fastener 15 arejoined to a sheet of film material 30 prior to the formation of the mainbag body 14.

More specifically, the female-fastening member 18 and the male-fasteningmember 19 are joined on one surface of the sheet of film material 30 soas to be spaced apart from each other as shown in FIG. 4, by placing thesheet of film material 30 between dies 31 and 32 of a linear-fastenermolding machine and injecting synthetic resin such as polyethylene resinin a molten state from a gate 33 of the die 32 to molding spaces throughrunners 34 by an insert injection molding. The length of each of thefemale-fastening member 18 and the male-fastening member 19 that formthe linear fastener 15 is not identical with the entire width L of themain bag body 14 to be formed, but has a length corresponding to avalue, which is obtained by subtracting the total width of the sideheat-sealed portions 16, 16 that are to be formed by a subsequentprocess, from the entire width L of the main bag body 14.

Now, description will be given below of a method for manufacturing theself-sanding reclosable packaging bag 10.

First, there are prepared three sheets of film material, i.e., thesheets of film material 11, 12 for forming the opposite faces of themain bag body 14 and the sheet of film material 13 for forming thebottom of the main bag body 14.

Then, the sheet of film material 13 for forming the bottom of the mainbag body 14 is folded in two. The folded sheet of film material 13 isplaced between the respective lower portions of the sheets of filmmaterial 11, 12 so that the folding edge 13 a of the folded sheet offilm material 13 is directed upward. A heat-sealing process is appliedto the lower portions of the sheets of film material 11, 12 and thesheet of film material 13 to form a heat-sealed lower portion 17.

Then, the upper portions 11 a, 12 a of the sheets of film material 11,12 having the heat-sealed lower portion 17 formed at their lower edgesare bent at right angles in opposite directions so as to be separatefrom each other. The upper portions 11 a, 12 a thus bent are placedbetween dies 20 and 21 of a linear-fastener molding machine as shown inFIG. 3.

Then, synthetic resin such as polyethylene resin or polypropylene resinis injected in a molten state from the gate 22 of the die 21 to themolding spaces through the runners 23, 23 by the insert injectionmolding, so as to extend on the bent upper portions 11 a, 12 a that areplaced between the dies 20 and 21 of the linear-fastener moldingmachine. The synthetic resin injected into the molding spaces in themolten state is cooled in these spaces. As a result, thefemale-fastening member 18 and the male-fastening member 19 that formthe linear fastener 15 are joined on the inner surfaces of the upperportions 11 a, 12 a of the main bag body 14, respectively. The length ofeach of the female-fastening member 18 and the male-fastening member 19is previously determined to be smaller than the entire width of the mainbag body 14 by the total width of the side heat-sealed portions 16, 16.

The bent upper portions 11 a, 12 a for the main bag body 14 are placedone upon another so that the male-fastening member 19 engages with thefemale-fastening member 18. A heat-sealing process is applied to theopposite side portions of the sheets of film material 11, 12 to formside heat-sealed portions 16, 16. The self-standing type reclosablepackaging bag 10 is prepared in this manner.

Now, description will be given below of a method for manufacturing athree-side-sealed type reclosable packaging bag.

First, a rolled strip of film material 30 is prepared. A part of therolled strip of film material 30, which is unrolled therefrom, is placedbetween dies 31, 32 of a linear-fastener molding machine as shown inFIG. 4.

Then, synthetic resin such as polyethylene resin is injected in a moltenstate from a gate 33 of the die 32 to molding spaces through runners 34,34 by an insert injection molding. As a result, the female-fasteningmember 18 and the male-fastening member 19 are joined on the one surfaceof the part of the rolled strip of film material 30 so as to be separatefrom each other. The length of each of the female-fastening member 18and the male-fastening member 19 is smaller than the entire width L ofthe main bag body 14 by the total width of the side heat-sealed portions16, 16.

The rolled strip of film material 30, which has the female-fasteningmember 18 and the male-fastening member 19 joined thereon, is cut offalong a line C to a length L corresponding to the entire width of themain bag body 14 to be formed. The cut sheet of film material 30 has thefemale-fastening member 18 and the male-fastening member 19 on theopposite edges, as shown in FIG. 6. The cut sheet of film material 30 isfolded in two along the intermediate line so that the female-fasteningmember 18 and the male-fastening member 19 engage with each other.

A heat-sealing process is applied to the opposite side portions of thesheet of film material 30, which has been folded in two, to form sideheat-sealed portions 16, 16. The three-side-sealed reclosable packagingbag is prepared in this manner.

Now, description will be given below of a method for manufacturing afour-side-sealed type reclosable packaging bag.

First, two sheets of film material 11, 12 for forming the opposite facesof the reclosable packaging bag. These sheets of film material 11, 12are placed one upon another. A heat-sealing process is applied to thelower portions of the sheets of film material 11, 12 to form a lowerheat-sealed portion 17.

The sheets of film material 11, 12 have the lower heat-sealed portion 17formed on their lower edges and the upper portions 11 a, 12 a, whichhave not as yet been joined with each other. Then, the upper portions 11a, 12 a of the sheets of film material 11, 12 are bent at right anglesin opposite directions so as to be separate from each other. The upperportions 11 a, 12 a thus bent are placed between the dies 20 and 21 ofthe linear-fastener molding machine as shown in FIG. 3.

Then, synthetic resin such as polyethylene resin is injected in a moltenstate from the gate 22 of the die 21 to the molding spaces through therunners 23, 23 by an insert injection molding, so as to extend on thebent upper portions 11 a, 12 a that are placed between the dies 20 and21 of the linear-fastener molding machine. As a result, thefemale-fastening member 18 and the male-fastening member 19 are joinedon the inner surfaces of the bent upper portions 11 a, 12 a. The lengthof each of the female-fastening member 18 and the male-fastening member19 is previously determined to be smaller than the entire width of themain bag body 14 by the total width of the side heat-sealed portions 16,16.

The bent upper portions 11 a, 12 a for the main bag body 14 are placedone upon another so that the male-fastening member 19 engages with thefemale-fastening member 18. A heat-sealing process is applied to theopposite side portions of the sheets of film material 11, 12 to formside heat-sealed portions 16, 16. The self-standing type reclosablepackaging bag is prepared in this manner.

FIG. 10 illustrates a packaged article, which is obtained by filling areclosable packaging bag with contents having a rectangular plate-shape.

The packaged article 40 comprises a three-side-sealed reclosablepackaging bag 41 and the contents (not shown) such as cookies, crackersor the like, having the rectangular plate-shape received in the bag 41.

Receipt of the contents having the rectangular plate-shape in thethree-side-sealed reclosable packaging bag 41 deforms the bag 41 into arectangular parallelepiped as shown in FIG. 7, which has a sidecorresponding to the shape of the contents. In this case, a portion ofthe bag, which includes the side heat-sealed portion, is deformed into aflat portion, while the opposite faces of the bag expand outward. As aresult, the width of the upper portion 42 of the deformed bag, whichincludes the linear fastener 15 and to which the contents do not come,is larger than the width of the lower portion of the deformed bag sothat the upper portion 42 projects from the above-mentioned flat portionin the width direction of the bag.

The upper portion 42 of the three-side-sealed reclosable packaging bag41 is folded along the upper horizontal plane of the contents as shownin FIG. 8, in order to form the packaged article 40 having therectangular shape as shown in FIG. 10. The opposite side edges of theupper portion 42 thus folded project from the above-mentioned flatportion including the side heat-sealed portion. The projecting portion43 is bent downward so as to be in parallel with the vertical side planeof the contents as shown in FIG. 9. In this case, it is preferable toprovide an easily bendable portion such as a notch on a portion of thelinear fastener 15, which corresponds to a bending line along which theprojecting portion 43 is to be bent, thus permitting an easy bendingprocess of the projecting portion 43.

Now, description will be given below of the reclosable packaging bag ofthe other embodiment of the present invention with reference to FIGS. 11and 12.

The reclosable packaging bag 50 comprises a main bag body 54, a linearfastener 55 and a sleeve 60.

The main bag body 54 is formed by folding a single sheet of filmmaterial in two so that the folding line locates downward andheat-sealing the opposite sides of it. More specifically, the main bagbody 54 has an opening at the upper portion and the heat-sealed portions56, 56 on the opposite sides.

The linear fastener 55 is provided along the opening of the main bagbody 54 in the same manner as in the embodiment as shown in FIG. 2. Morespecifically, a male-fastening member for the linear fastener is formedon the inner surface of one of the opposing portions 51, 52 of the sheetof film material for forming the main bag body 54, in the vicinity ofthe opening thereof, and a female-fastening member for the linearfastener is formed on the inner surface of the other of the opposingportions 51, 51 thereof. The male and female-fastening members for thelinear fastener 55 are provided on the portions of the sheet of filmmaterial, excepting the heat-sealed portions 56, 56.

The sleeve 60 is formed of bendable material such as paper, syntheticresin or the like. The sleeve 60 is composed of a pair of opposing frontand rear face portions 60 a, 60 b and a pair of side face portions 60 c,60 d that are provided so as to connect the opposite edges of the frontand rear face portions 60 a, 60 b with each other and have projections60 cx, 60 dx having a triangular shape, respectively. The front and rearface portions 60 a, 60 b have the same rectangular shape. The side faceportions 60 c, 60 d have the same pentagonal shape, i.e., the shapeobtained by combining a rectangle with an isosceles triangle locatingbelow it. Each of the side face portions 60 c, 60 d has a folding lineFL, which is formed in the central portion in its width direction so asto extend the longitudinal direction, as shown in FIG. 12( a).Accordingly, the sleeve 60 may have the three-dimensional structure asshown in FIG. 12( a) and be folded in a flat state as shown in FIG. 12(b) by bending the side face portions 60 c, 60 d along the folding linesFL of the side face portions 60 c, 60 d, while moving the folding linesFL outward.

The sleeve 60, which is kept in the folded state as shown in FIG. 12(b), is inserted into the main bag body 54 so that the peaks of theprojections 60 cx, 60 dx come into contact with the bottom of the mainbag body 54.

Changing the shape of the sleeve, which has been inserted into the mainbag body 54, into the three-dimensional shape as shown in FIG. 12( a)causes the main bag body 54 to be kept in the shape as shown in FIG. 16(f) (although the main bag body 74 used in the embodiment as shown inFIG. 16( f) differs from the main bag body 54 as shown in FIG. 11 in theformer has a single heat sealed-portion). In such a state, theself-standing shape can be provided by bending inward the projections 60cx, 60 dx of the sleeve 60 together with the main bag body 54. Thereclosable packaging bag 50 can be changed into a stackable rectangularparallelepiped by bending the upper portions of the main bag body 54 asshown in FIGS. 8, 9 and 10.

The linear fastener 55 is also bent so as to coincide with therectangular parallelepiped shape when bending the upper portions of themain bag body 54. The linear fastener 55 has easily bendable portions 58a, 59 a as shown in FIG. 13 so as to facilitate the above-mentionedbending operation.

The linear fastener 55 has the female-fastening member 58 and themale-fastening member 59 in the same manner as the embodiment as shownin FIG. 2. The easily bendable portions 58 a, 59 a comprise flatportions, which are formed by removing partially the female-fasteningmember 58 and the male-fastening member 59 in the bending portions,i.e., the portions corresponding to the upper edges of the side faceportions 60 c, 60 d of the sleeve 60. Accordingly, the easily bendableportions 58 a, 59 a has neither female-receiving portion normale-engaging portion, which are provided in the other region, and hasonly the flat plate portion. It is therefore possible to bend easily thelinear fastener 55 without causing unseemly outward projection of thebent portions, thus providing a nice-looking stackable rectangularparallelepiped shape of the reclosable packaging bag.

The easily bendable portions are not limited only to the above-describedstructure. The easily bendable portions may be formed as holes that areobtained by a punching operation or the like in the correspondingbending portions of the female-fastening member 58 and themale-fastening member 59, thus facilitating the bending step.

The formation of the easily bendable portions 58 a, 59 a only in thebending portions of the linear fastener 55 will suffice. The easilybendable portions 58 a, 59 a do not remarkably deteriorate the sealingproperty by the linear fastener 55. However, when there is a demand foran excellent sealing property of the reclosable packaging bag, it ispreferable to provide the easily bendable portions 58 a, 59 a withauxiliary sealing means 58 b, 58 b, 59 b, 59 b as shown in FIG. 14.

The auxiliary sealing means comprise a pair of ribs 58 b, 58 b having atriangular cross-section, which are formed integrally with the flatportion 58 a for the female-fastening member 58 so as to project towardthe male-fastening member 58 and a pair of ribs 59 b, 59 b having atriangular cross-section, which are formed integrally with the flatportion 59 a for the male-fastening member 59 so as to project towardthe female-fastening member 58. The tip end portions of the ribs 58 b,58 b for the female-fastening member 58 come into contact with the tipend portions of the ribs 59 b, 59 b for the male-fastening member 59,respectively, so as to improve the sealing property between the flatportions 58 a, 59 a, in the sealing state of the linear fastener 55,i.e., in a state in which the male-fastening member 59 engages with thefemale-fastening member 58.

The projection height of the ribs 58 b, 58 b and 59 b, 59 b aresubstantially identical with half of the depth of the female-receivingportion of the female-fastening member 58 and half the height of themale-engaging portion of the male-fastening member 59, respectively. Asa result, these ribs 58 b, 58 b and 59 b, 59 b do not deteriorate theeasily bending property of the easily bendable portions 58 a, 59 a.

The ribs 58 b, 58 b and 59 b, 59 b as shown in FIG. 14 locate so as tobe apart outside from the opposite sides of the female-receiving portionof the female fastening member 58 and the opposite sides of the maleengaging portion of the male-fastening member 59 by a prescribedistance. Provision of the ribs 58 b, 58 b and 59 b, 59 b in thevicinity of the female-receiving portion and the male engaging portionmentioned above permits to ensure a further excellent sealing property.

The above-mentioned auxiliary sealing means are not limited only to theabove-mentioned structure. As shown in FIG. 15, they may comprise a pairof ribs 59 c, 59 c having a trapezoidal cross-section, which are formedintegrally with the flat portion 58 a for the female-fastening member 58so as to project toward the male-fastening member 58 and a pair of ribs59 c, 59 c having a trapezoidal cross-section, which are formedintegrally with the flat portion 59 a for the male-fastening member 59so as to project toward the female-fastening member 58. In this case,the upper surface portions of the ribs 58 c, 58 c for thefemale-fastening member 58 come into contact with the tip lower surfaceportions of the ribs 59 c, 59 c for the male-fastening member 59,respectively, so as to improve the sealing property between the flatportions 58 a, 59 a, in the sealing state of the linear fastener 55,i.e., in a state in which the male-fastening member 59 engages with thefemale-fastening member 58.

Now, description will be given below of a method for manufacturing thereclosable packaging bag of the other embodiment described above of thepresent invention.

The manufacturing method of the present invention comprises apreparation step for a non-joined main bag body for a packaging bag, anposition adjustment and folding step, a cutting and bending step, alinear fastener forming step, a heat-sealing step and a sleeve-insertionstep.

The preparation step for the non-joined main bag body is carried out byplacing the opposite ends of a single sheet of film material 70 f oneupon another and heat-sealing the overlapping portions of the sheet overtheir entirety in the longitudinal direction to form a heat-sealedportion 76, thus preparing the non-joined main bag body having the upperand lower openings (see FIG. 16( a)).

The position adjustment and folding step is carried out by turning thenon-joined main bag body in its circumferential direction so that theinside edge of the above-mentioned heat-sealed portion 76 is apart fromthe one side edge by a prescribed distance “d” and folding it in a flatstate (see FIG. 16( b)). The distance “d” is substantially identicalwith the half of the width of the side face portion 60 d of the sleeve60, which is used in the sleeve-insertion step, i.e., the length “L” asshown in FIG. 12( b).

The cutting and bending step is carried out by forming cut-outs CL atthe upper ends of the opposite side edges of the non-joined main bagbody after the completion of the position adjustment and folding step,and then folding the upper portions of the non-joined main bag body,which correspond to the length of the cut-outs CL, so as to be separatefrom each other to form a pair of bent portions (see FIG. 16( c)).

The linear fastener forming step is carried out by placing the pair ofbent portions in a linear-fastener molding machine and continuouslyforming the linear fastening members for the linear fastener on theinner surfaces of the pair of bent portions of by an insert injectionmolding, respectively, excluding opposite side edges thereof. The linearfastener forming step is identical with the linear fastener forming stepin the embodiment as shown in FIG. 2. The description of it is thereforeomitted.

The heat-sealing step is carried out by heat-sealing the lower edge ofthe non-joined main bag body over its entirety in the width direction ofthe bag to form a heat-sealed portion 77 and heat-sealing only the upperends of the opposite side edges of the non-joined main bag body, whichcorrespond to the cut-outs CL (see FIG. 16( d)). The main bag body 74 isprepared in this manner.

The sleeve-insertion step is carried out by inserting the sleeve 60 intothe main bag body 74 (see FIG. 16( e)). The sleeve 60 is the same asthat described in the embodiment as shown in FIGS. 11 and 12. Thedescription of it is therefore omitted.

Changing the shape of the sleeve 60, which has been inserted into themain bag body 74, into the three-dimensional shape as shown in FIG. 12(a) causes the main bag body 74 to be kept in the shape as shown in FIG.16( f). In such a state, the self-standing shape can be provided bybending inward the projections 60 cx, 60 dx of the sleeve 60 togetherwith flap portions 70 a, 70 b of the main bag body 74. The reclosablepackaging bag 70 can be changed into a stackable rectangularparallelepiped by bending the upper portions of the main bag body 74 asshown in FIGS. 8, 9 and 10.

In the reclosable packaging bag 70 formed in the manner as mentionedabove, the non-joined main bag body is turned in its circumferentialdirection so that the inside edge of the heat-sealed portion 76 is apartfrom the one side edge by the prescribed distance “d”, i.e., the length“L” as shown in FIG. 12( b). Accordingly, it is possible to place theheat-sealed portion 76 in the vicinity of the edge of the side face ofthe reclosable packaging bag 70 having the rectangular parallelepiped.The heat-sealed portion 76 therefore become inconspicuous, to keep anice-looking external appearance of the reclosable packaging bag 70.

When the demand for improvement in the external appearance is not sosevere, there may be omitted the step for turning the non-joined mainbag body in its circumferential direction in the above-mentionedmanufacturing method. When such a turning step is omitted, theheat-sealed portion is placed in the central portion of the side face ofthe reclosable packaging bag 70 having the rectangular parallelepiped.

Now, description will be given below of another method for manufacturingthe reclosable packaging bag of the other embodiment described above ofthe present invention.

The other manufacturing method of the present invention comprises asheet-folding step, a sleeve-placing step, a cutting and bending step, alinear fastener forming step and a heat-sealing step.

The sheet-folding step is carried out by folding a single sheet of filmmaterial 80 f in two to prepare a non-joined main bag body the upper andlower edges and one side edge of which have not as yet been joined.

The sleeve-placing step is carried out by placing the sleeve 60 in thenon-joined main bag body (see FIG. 17( a)). The sleeve 60 may betemporarily secured to the non-joined main bag body by an adhesion meanssuch as a hot-melting method. The sleeve 60 is the same as thatdescribed in the embodiment as shown in FIGS. 11 and 12. The descriptionof it is therefore omitted.

The cutting and bending step is carried out by forming a cut-out at theupper end of one side edge of the non-joined main bag body, and thenfolding the upper portions of the non-joined main bag body, whichcorrespond to the length of the cut-out, so as to be separate from eachother to form a pair of bent portions.

The linear fastener forming step is carried out by placing the pair ofbent portions in a linear-fastener molding machine and continuouslyforming the linear fastening members for the linear fastener on theinner surfaces of the pair of bent portions of by an insert injectionmolding, respectively, excluding opposite side edges thereof. The linearfastener forming step is identical with the linear fastener forming stepin the embodiment as shown in FIG. 2. The description of it is thereforeomitted.

The heat-sealing step is carried out by heat-sealing the lower edge ofthe non-joined main bag body over its entirety in the width direction ofthe bag to form a lower edge heat-sealed portion 87, heat-sealing theother side edge over its entirety in the longitudinal direction to aside heat-sealed portion 86 and in addition, heat-sealing only the upperend of the one side edge of the non-joined main bag body, whichcorrespond to the cut-out (see FIG. 17( b)). The main bag body 84 isprepared in this manner.

Changing the shape of the sleeve 60, which has been inserted into themain bag body 84, into the three-dimensional shape as shown in FIG. 12(a) causes the main bag body 84 to be kept in the shape as shown in FIG.17( c). In such a state, the self-standing shape can be provided bybending inward the projections 60 cx, 60 dx of the sleeve 60 togetherwith the main bag body 84. The reclosable packaging bag 80 can bechanged into a stackable rectangular parallelepiped by bending the upperportions of the main bag body 84 as shown in FIGS. 8, 9 and 10.

When a co-extrusion film or the like, which has on its opposite surfacesa heat-sealing property, is used as the sheet of film material in theabove-described method for manufacturing the reclosable packaging bag,it is possible to prevent the heat-sealed portion from projectingoutward by applying an easy heating treatment to the reclosablepackaging bag having the three-dimensional shape. It is thereforepossible to impart a nice-looking appearance to the reclosable packagingbag having the three-dimensional shape. In addition, it is also possibleto prevent a display condition of the packaging bags on a display shelfin a retail store from being disordered and the packaging bags fromfalling down from the display shelf due to entanglement of theheat-sealed portion of the packaging bag with that of the otherpackaging bag.

In the above-mentioned embodiment of the present invention, the sleevehas a shape as shown in FIG. 12. The sleeve is not limited only to theabove-mentioned shape and may have any other shape by which thepackaging main bag body can be kept in a prescribed shape.

The present invention also includes a reclosable packaging bag, whichpermits to solve the problem of improvement in stacking property. Thereclosable packaging bag, which has fundamental elements of a main bagbody having an opening and at least one heat-sealed portion and of alinear fastener provided on the opening portion of the main bag body, isfurther provided with a sleeve that is placed in the main bag body. Thereclosable packaging bag is characterized in that the main bag body isfolded into a prescribed three-dimensional shape defined by the sleeveso as to keep the prescribed three-dimensional shape.

As a result, in the above-mentioned reclosable packaging bag of thepresent invention, it is not always necessary to form the linearfastener by an insert injection unlike the above-mentioned embodimentsof the present invention. More specifically, the linear fastener thathas previously been formed may be fitted onto a prescribed place of themain bag body by adhesive agent, a thermal bonding process that is to besimultaneously applied during the heat-sealing process, or any otherappropriate fitting means. In this case, it is preferable to form thinportions at the opposite ends of the linear fastener and/or easilybendable portions on portions thereof to be bent in the same manner asthe above-described embodiments of the present invention. The reclosablepackaging bag does not always require these features, when the demandfor improvement in the external appearance is not so severe.

In the above-described embodiments of the present invention, each of theprojections 60 cx, 60 dx of the sleeve 60 has a function of coming intocontact with the bottom of the main bag body 54, 74, 84 to maintain aprescribed position of the sleeve 60 in the main bag body 54, 74, 84. Ifthe main bag body has such a function, the projections 60 cx, 60 dx ofthe sleeve are not required. With respect to such a kind of reclosablepackaging bag, the other embodiment of the present invention will bedescribed below with reference to FIGS. 18 and 19.

The reclosable packaging bag 90 comprises a main bag body 94, a linearfastener 95 and a sleeve 60M1.

Opposing portions 91, 92 and heat-sealed portions 96, 96 of the main bagbody 94 of the reclosable packaging bag 90 as shown in FIG. 18correspond to the opposing portions 51, 52 and the heat-sealed portions56, 56 of the main bag body 54 of the reclosable packaging bag 50 asshown in FIG. 11, respectively. Each of the heat-sealed portions 96, 96is provided on its lower portion with a stopper portion 96 a. Thestopper portions 96 a, 96 a face each other as shown in FIG. 18 so thatthe opposite lower side edges of the sleeve 60M1 are placed on thestopper portions 96 a, 96 a. Each of the stopper portions 96 a, 96 a isformed by increasing the width of the lower portion of the heat-sealedportion 96 as shown in FIG. 19( a). The stopper portions 96 a, 96 a havea function of maintaining the prescribed position of the sleeve 60 inthe main bag body 94 so that the lower portion of the main bag body 94can easily be folded into a shape as shown in FIG. 8. The sleeve 60M1therefore has no projections unlike the sleeve 60 described above.

The stopper portion 96 a is preferably formed on each of the heat-sealedportions 96, 96 as shown in FIG. 18. However, the single stopper portionmay be formed on any one of the heat-sealed portions 96, 96. The stopperportion 96 may be formed by increasing partially the width of the lowerportion of the heat-sealed portion 96 as shown in FIG. 19( b) so as toform a small projection 96 b. The reclosable packaging bag 90 is foldedinto the shape as shown in FIG. 8 in the same manner as described above.

FIG. 20 illustrates a modification 60M2 of the sleeve 60M1 as shown inFIG. 18. The modified sleeve 60M2 has a pair of bendable reinforcementflaps 60 cy, 60 dy. More specifically, the sleeve 60M2 is composed of apair of opposing front and rear face portions 60 a, 60 b and a pair ofside face portions 60 c, 60 d. The reinforcement flaps 60 cy, 60 dy areintegrally formed with the upper edges of the side face portions 60 c,60 d of the sleeve so as to project upward. FIG. 20( a) illustrates thesleeve 60M2, which is folded into a flat state. The shape of the sleeve60M2 folded in such a flat state is changed into a rectangular shape byunfolding the side face portions 60 c, 60 d. The reinforcement flaps 60cy, 60 dy can be bent inward as shown in FIG. 20( b) so as to increasethe strength of the unfolded sleeve 60M2. It is preferable to providethe side face portions 60 c, 60 d with the reinforcement flaps 60 cy, 60dy, respectively. A single reinforcement flap may however be provided onone of the side face portions 60 c, 60 d.

FIG. 21 illustrates the other modification 60M3 of the sleeve 60M2 asshown in FIG. 20. The sleeve 60M3 is identical to the sleeve 60M2 exceptthat the former has a detachable cover portion 60 dy. The same referencenumerals are given to the same structural elements and the descriptionof these elements is omitted. The cover portion 60 dy is formed byincreasing the length of the reinforcement flap 60 dy as shown in FIG.20( b). The length of the cover portion 60 dy is substantially identicalwith the width of the front face portion 60 a. The cover portion 60 dycan be turned so that the tip end of the cover portion 60 dy is placedon the reinforcement flap 60 cy as shown in FIG. 21( b). Such astructure permits to increase further the strength of the unfoldedsleeve 60M3. The connection portion of the cover portion 60 dy with theside face portion 60 d is provided with a line of perforations so thatthe cover portion 60 dy can easily be detached from the side faceportion 60 d. Finger holes 60 dya, 60 dyb are formed on the coverportion 60 dy to facilitate detachment thereof from the side faceportion 60 d.

There may be provided a cover, which is formed separately from thesleeve and has an inverse U-shape so as to be inserted into the sleeve,in replacement of the above-described detachable cover portion 60 dy.

In the above-described embodiments of the method for manufacturing thereclosable packaging bag, the bottom of the reclosable packaging baghaving a stackable rectangular parallelepiped shape is formed by bendingthe flap portions 70 a, 70 b inward as shown in FIG. 22. When aco-extrusion film or the like, which has a heat-sealing property, isused as the sheet of film material, it is possible to prevent the flapportions 70 a, 70 b from projecting downward by applying an easy heatingtreatment to the bottom of the reclosable packaging bag.

FIGS. 23 and 24 illustrate a modified formation method of the bottom ofthe reclosable packaging bag 100. The modified formation methodcomprises the steps of subjecting flap portions 100 a, 100 b of the mainbag body 104 to a heat-sealing process and cutting off the tip endportions of them.

More specifically, the flap portion 100 a of the main bag body 104 isplaced on a base 111 and a heat-sealing head 110 is pressed on the flapportion 100 a to achieve the heat-sealing process. The heat-sealingprocess is applied to the other flap portion 100 b of the main bag body104 in the same manner. The heat-sealed flap portions 100 a, 100 b areprovided in this manner as shown in FIG. 23( b). Then, the tip endportions of the heat-sealed flap portions 100 a, 100 b are cut off asshown in FIG. 24( a) to form small flaps 100 ax, 100 bx. FIG. 24( b) isa schematic view illustrating the reclosable packaging bag 100, theshape of which is changed into a rectangular parallelepiped. In FIG. 24(b), reference numerals “100 x, 100 y” denote upper flap portions of thereclosable packaging bag 100, which are kept in a folded state. In sucha reclosable packaging bag 100, there is not required any step forfolding the flap portions inward as shown in FIG. 10. In addition, thesmall flaps 100 ax, 100 bx improve the self-standing property of the bag100. The small flaps 100 ax, 100 bx may however be folded inward asshown in FIG. 10.

In the above-described embodiments of the present invention, the linearfastener may have a slider that is movable along the linear fastener soas to open or close the opening portion of the main bag body. The sleevemay have at lease one portion, which is joined to the main bag body by asuitable joining means such as adhesive, heat-sealing or the like. Theshape of projections of the sleeve is not limited only to a triangle,but may be a trapezoid.

According to the present invention described above, the linear fasteneris provided along the opening portion of the main bag body by the insertinjection molding so as not to extend to the heat sealed portions. It istherefore possible to reduce the period of time for process and improvethe processing efficiency.

When the main bag body includes the sleeve for keeping the prescribedshape of the main bag body, it is possible to change easily the main bagbody into a proper three-dimensional shape. In addition, it is alsopossible to impart an appropriate strength to the three-dimensional mainbag body so as to bear sufficiently the stacking load.

Provision of the easily bendable portion on the linear fastenerfacilitates the folding of the main bag body, so as to make it possibleto prevent the occurrence of unseemly outward projection of the bentportions, thus providing a nice-looking appearance of thethree-dimensional main bag body.

1. A method for manufacturing a reclosable packaging bag, whichcomprises the steps of: providing at least two sheets of film material,each sheet of film material having opposing upper and lower edges andopposing side edges; placing said at least two sheets of film materialone upon another to prepare a non-joined main bag body, wherein saidupper and lower opposing edges and said opposing side edges of eachsheet of film material have not as yet been joined with any opposingedge; folding upper portions of said at least two sheets of filmmaterial so as to separate the upper portions of said at least twosheets of film material to form a first and second bent portions,thereby exposing inner surfaces of said at least two sheets of filmmaterial; placing said first and second bent portions in alinear-fastener molding machine; continuously forming a first linearfastening member on the inner surface of one of said first and secondbent portions and forming a second linear fastening member on the innersurface of the other of said first and second bent portions of saidnon-joined main bag body by an insert injection molding, respectively,excluding opposite side edges of each bent portion thereof; andheat-sealing said lower edge and said left-hand and right-hand sideedges of said at least two sheets of film material over their entiretyto form a joined main bag body.
 2. The method as claimed in claim 1,further comprising the step of: inserting a sleeve for keeping aprescribed shape of said main bag body thereinto, after completion ofthe final step.
 3. The method as claimed in claim 1, further comprisingthe step of: placing a sleeve for keeping a prescribed shape of saidmain bag body in said non-joined main bag body.